Calutron protective circuit



May 2 6, 1959 F. H. SCHMIDT cALUTRoN PROTECTIVE CIRCUIT Filed June 10, 1946 lNvE NToR FRED H. ScHMmT ATToRNrsf Atal 2530() United States Patent O 2,888,564 CALUTRON PROTECTIVE CIRCUIT Fred H. Schmidt, Berkeley, Calif., assigner to the United States of America as represented by the United States Atomic Energy Commission Application June 10, 1946, Serial No. 675,567 3 Claims. (Cl. Z50-41.9)

This invention relates to an arrangement for preventing the inadvertent overheating of water-cooled structure associated with the calutron ion source.

A calutron is an electron magnetic mass separation apparatus of the type disclosed 4in U.S. Patent No. 2,709,222 issued May 24, 1955 to Ernest Orlando Lawrence, for calutrons.

An object of this invention is to provide a calutron with apparatus controlled by the iiow of a cooling medium through a conduit associated with the ion source of the calutron, said apparatus being operable to permit an arc to be established in said ion source only when the rate of ow of the -cooling medium through said conduit exceeds a predetermined rate. v

vOther and further objects of this invention will be apparent to those skilled in the art to which it relates from the following specification, claims and drawing.

Referring to the drawing briefly, the sole figure illustrates a schematic wiring diagram of an embodiment of this invention.

In order to prevent inadvertent overheating of watercooled structure associated with a calutron ion source, the water supply associated with this structure is interlocked with the electrical supplies which produce heating of the ion source.

Referring to the sole ligure of the drawing there is diagrammatically illustrated a typical calutron of the type to which the present invention has been applied, together with the associated electrical networks. This calutron includes a C-shaped tank 11 which is maintained at a low pressure by means of a vacuum pump 12. This tank 11 is arranged in the air gap of an electromagnet (not shown).

An ion beam transmitter 15 and an isotope collector 16 are arranged within the tank at opposite ends thereof in the general manner described in the aforesaid Lawrence patent. The collector 16 is provided with two pockets 17 and 18 in which monoisotopically enriched material is to be collected. The ion transmitter 15, illustrated here, includes an ion source 20 and an ion accelerating electrode structure 21.

The ion source comprises a charge chamber 22 and an arc chamber 23 communicated therewith, two corresponding electrical heaters 24 and 25 respectively associated therewith, and a thermionically emissive cathode 26 operatively associated with the arc chamber 23. The arc chamber 23 includes an upstanding slit 27 at the side thereof adjacent the ion accelerating structure 21. The ion accelerating structure incorporates two spaced-apart electrodes forming a beam defining slit 28 disposed adjacent and parallel to the slit 27 in the arc chamber 23.

The charge chamber 22 and arc chamber 23 are supported from the wall of ythe tank 11 by means of an insulating bushing 30. The thermionically emissive cathode 26 is supported above the arc chamber 23 by means of two rigid leads 31 and 32 in the form of squirt tubes extending through and insulated from the wall of the tank 11.

2,888,564 Patented May 26, 1959 ICC The leads 31 and 32 and the bushing 30 are watercooled by means of water supplied through a main conduit 33, including a valve 34 and a ow switch 35 and two branch conduits 37 and 38. The branch conduit 37 isarranged in heat exchange relation with the bushing 30. Water is supplied to the two leads 31 and 32 through the other branch conduit 38. To electrically insulate the water supply from the ion source 20 the main conduit 33 enters a central opening of an insulating T junction 40 connected at its two opposite ends to the two branch conduits 67 and 38. As mentioned, part of the first of these branch conduits 37 is mounted in heat exchange relation with the bushing 30. The second of these branch conduits 38 communicates with an insulating block 41 which is connected to the outer ends of the squirt tubes 31 and 32. This insulating block 41 is so arranged that cooling water flows through the branch conduit 38 into the block 41, hence through one squirt tube 31 back into the block 41 and thence through the second squirt tube 32 back into the block 41 and thence out of the block 41. In operation the water ows through the iiow switch |35 into the insulating T junction 40 and thence into the two branch conduits 37 and 38 through the two squirt tubes 31 and 32 and through part of the conduit 37 associated with the bushing 30 and thence into a waste system (not shown).

In order to strike an arc in the arc chamber 23 and to control it in a suitable manner electrical power is supplied to the heaters 24 and 25 associated with the charge chamber 22, the arc chamber 23 and also to the thermionically emissive cathode 26. The heating of the charge chamber 22 causes a charge of solid material previously placed therein to vaporize and flow into the arc chamber 213 where it becomes ionized and some of the ions formed are withdrawn through the slit 27 through the beam defining slit 28 in the accelerating electrode structure and are thence projected along arcuate paths to the collector 16. In the calutron 10 illustrated here the accelerating electrode structure 21 is electrically connected to the wall of the tank 11 and is grounded and the ion source 20 is maintained at a high positive potential with respect to ground in a manner hereinafter described. y

The thermionically emissive cathode 26 and the electrical heaters 24 and 25 are supplied power through corresponding first, second, and third power supplies 50, 60, and 70 respectively associated therewith. The first power supply 50 includes a manually operable switch 51, a variac 52, an isolation transformer 53, and a radio frequency oscillator 54 arranged in the order named between the input 55 and the output 56 thereof. A lament supply circuit 57 is associated with the oscillator 54. The second power supply 60 comprises a manually operable switch 61, a variac 62, and an isolation transformer 63 operatively connected in the order named between the input 64 and the output 65 thereof. And the third power supply 79 comprises a manually operable switch 71, a variac 72, and an isolation transformer 73 operatively connected in the order named between the input 74 and the output 75 thereof.

An arc voltage supply S0 having an input 81 and an output 82 is provided, the output 82 of which is electrically connected between the arc chamber 23 and the cathode 26 so as to maintain the cathode 26 negative with respect to the arc chamber 23 by means of a suitable voltage of about fifty to two hundred volts. The inputs S1, 55, 64, and 74 of the arc voltage supply 80 and the first, second, and third power supply 50, 60, and 70 mentioned above are all connected to conductors 91 of a main power line thro-ugh contacts 93 of a relay 94. The coil 95 of the relay 94 is connected across the conductors 91 of the main power line through contacts to a microswitch element (not shown) in the ow switch 35.

There is also provided a regulated high voltage supply 100 having an input 101 and an output 102 adapted to produce a high D.C. voltage of the order of about 10,000 to about 20,000 volts. The output 102 of this power supply is connected between the ion source 20 and the grounded accelerating electrode structure 21 with the ionl chamber 23. When an arc of suitable strength and stability is thus established in the arc chamber 23, the switch 108 is closed, thus causing the regulated voltage supply to become energized and thus establishing an ion accelerating iield between the ion source and the accelerating electrode structure 21. When the eld has been established some of the' ions formed in the arc chamber 23 are withdrawn therefrom and selected ions are projected along arcuate paths through `the tank 11 to the collector V16 where monoisotopically enriched material derived from the polysotopic charge material are separately collected in the pockets 17 and 18.

By means of the arrangement described, no arc can be established in the arc chamber unless water is 'owing regulated high voltage supply 100 is connected tothe Y conductors 106 through another double pole single throw switch 108. The input 81 of the arc voltage supply 80 is connected to the conductors 90 through a double pole single throw switch 84. To complete the electrical control network associated with the calutron 10 there is provided a vacuum pump control circuit 110 having an input 111 and an output 112 and a magnet control circuit 120 having an input 121 and an output 122. The inputs 111 and 121 of these two circuits are connected to the conductors 91 of the main power line through corresponding double pole single throw switches 113 and 123. The output 112 of the vacuum pump control circuit 110 is connected to the vacuum pump 12. The output 122 of the magnet control circuit 120 is applied to the coils (not shown) of the electromagnet in the gap of which the calutron 10 is mounted.

In operation, in order to effect an isotopic separation and a collection of the separated isotopes, a charge of solid polyisotopic material is placed in the charge chamber 22 and the ion source is mounted in a standard manner within the tank 11. The switches 113 associated with a vacuum pump control circuit 110 is then closed, thus energizing the vacuum pump and initiating evacuation of the tank 11. After the pressure within the tank 11 has been reduced to suitably low value of the order of` l0*4 mm. Hg the switch 123 associated with the magnet control circuit 120 is energized, thereby establishing a magnetic eld through the tank'll. The switch 107 is then closed, thus energizing the lament supplies 103, 104, and 57. The valve 34 in the main water conduit 33 is then opened causing cooling Water to circulate through the squirt tubes 31 and 32 and through the part of the conduit 37 arranged on the bushing 30. When the rate of ow of cooling water is thus established, a microswitch (not shown) in the flow switch 35 is closed, thus completing the circuit including the coil 95, and thus energizing the relay 94. When the relay 94 is thus energized the contacts 93 close and the conductors 90 are electrically connected to conductors 91 of the main line, thus preparing the three power supplies 50, 60, and 70 for operation. The switches 51, 61, and 71 of these three power supplies are then closed, thereby causing Aelectrical energy to ow to the thermionically emissive cathode 26, and the two heaters 24 and 25. The amount 5f heat supplied to the cathode 26 and to these two heaters 24 and 25 is regulated by adjustment of the corresponding variacs 52, 62, and 72. The switch 84 is also closed, thus establishing an electron accelerating voltage between the cathode 26 and the arc chamber 23 and causing ionzing electrons to be projected into the vapor in the arc at a suitable rate through various water-cooled structural elements associated with the arc chamber. This invention has also been applied to ion sources having water-cooled electron oscillation suppressors and water-cooled gunk catchers associated with the ion source.

What is claimed is:

1. In a calutron having an evacuated tank, an ion source including an arc genertaor in said tank, auxiliary structure arranged in thermal communication with said arc generator, cooling means including a conduit arranged in heat exchange relationship with said auxiliary structure, a source of electrical power, means controlled by flow of cooling medium through said conduit at a rate in excess of a predetermined rate for opreatively connecting said arc generator to said source of electrical power, whereby an arc is established in said ion source only when the rate of flow of the cooling medium through said conduit exceeds said predetermined rate. v

2. In a calutron having an evacuated tank, an ion source including'an arcl generator, mounting structure supporting said ion source in said tank, cooling means including a conduit arranged in heat exchange relationship with said mounting structure, a supply of electrical power associated with said arc generator for establishing an arc` in said ion source whereby said ion source is heated, a control network associated with said arc generator, means controlled by ow of a cooling medium through said conduit at a rate in excess of a predetermined rate for energizing said control network, and switching means included in said network for operatively connecting said arc generator to said electrical power supply, whereby an arc is established in said ion source only when the rate of flow of thecooling medium through said conduit exceeds said predetermined rate.

3. In a calutron having an evacuated tank, an ion source including a charge chamber and an arc chamber, two heaters respectively associated with said charge chamber and said arc chamber, a thermionically emissive cathode operatively associated with said arc chamber, auxiliary structure arranged in thermal communication with said ion source, cooling means including a conduit arranged in heat exchange relationship with said structure, a source of electrical power, a control network associated with said cathode and said heaters, means controlled by ow of a cooling medium through said conduit at a rate in excess of a predetermined rate for energizing said control network, and means included in said network for operatively connecting said source of electrical power to said cathode and said heaters, whereby an arc is established in said ion source only when the rate ofv ow of the cooling medium through said conduit exceeds said predetermined rate.

No references cited. 

